Method for preparing profiles

ABSTRACT

A method for updating profiles is provided. The method involves storing a plurality of successive profiles for an image recording device, and changing at least two of the successive profiles when characteristics of the image recording device change. The profiles are successively used to process image data that is used for recording images on a recording medium by the image recording device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of preparing upstream profilesand downstream profiles which are used for processing image data beforethe image data is used in a recording process in a manner that theupstream profiles are used for performing prior processes onto imagedata and the downstream profiles are used for performing subsequentprocesses onto the image data which has already been subjected to theprior processes.

2. Description of Related Art

There has been known an image forming device, such as a color printer,that records color images on a recording medium using four colors ofink, for example, cyan (C), magenta (M), yellow (Y), and black (K) ink.It is noted that the density level, actually outputted onto therecording medium, can vary according to a variety of conditions, such asthe model of the printer, the resolution, the type of ink, and the typeof recording medium. Therefore, according to the variation in thoseconditions, it will become impossible to faithfully reproduce colorimages, which are retrieved using a scanner, or prepared in a computer,if they are recorded onto a recording medium according to image datainputted as is from the computer or the scanner.

For this reason, before recording an image on a recording medium basedon image data inputted from a computer or the like, normally the inputimage data is first corrected based on profiles in order to reproduceoriginal images as faithfully as possible.

SUMMARY OF THE INVENTION

Examples of profiles include upstream and downstream profiles. Theupstream profile is used for performing prior processes on the inputimage data. The downstream profile is used for performing subsequentprocesses on the input image data, which has already been subjected tothe prior processes using the upstream profile. The image data thussubjected to the downstream profile is then used for recording acorresponding image onto a recording medium.

More specifically, the upstream profile is for correcting tone of inputimage data in order to correct for changes due to passage of time, forunique characteristics of the image recording device itself, and forother factors. The downstream profile is for further calibrating theinput image data, already subjected to the tone correction based on theupstream profile, in order to more precisely correct for the changes dueto passage of time, for the unique characteristics of the imagerecording device itself, and for other factors.

Because the upstream profile and the downstream profile are interrelatedin this way, the upstream profile, which will be used during the priorprocess, should be prepared after the downstream profile, which will beused during the subsequent process, is prepared.

It is an objective of the present invention to provide a method ofefficiently preparing the interrelated upstream and downstream profiles.

In order to attain the above and other objects, the present inventionprovides a method for preparing an upstream profile and a downstreamprofile, both of which are for being used to process image data forrecording images on a recording medium, the upstream profile being usedfor performing a prior process onto the image data and the downstreamprofile being used for performing a subsequent process on the image dataalready processed by the prior process, the method comprising the stepsof: preparing a downstream profile; preparing an upstream profile usingthe prepared downstream profile; and judging, after the downstreamprofile preparation process and before the upstream profile preparationprocess, whether the downstream profile has been properly prepared, andwhen it is judged that the downstream profile has been improperlyprepared, preventing the upstream profile preparation process from beingperformed based on the improperly-prepared downstream profile.

According to another aspect, the present invention provides an apparatusfor preparing an upstream profile and a downstream profile, both ofwhich are for being used to process image data for recording images on arecording medium, the upstream profile being used for performing a priorprocess onto the image data and the downstream profile being used forperforming a subsequent process on the image data already processed bythe prior process, the apparatus comprising: a downstream preparing unitpreparing a downstream profile; an upstream preparing unit preparing anupstream profile using the prepared downstream profile; and a judgingunit judging, after the downstream profile preparation process andbefore the upstream profile preparation process, whether the downstreamprofile has been properly prepared, and when it is judged that thedownstream profile has been improperly prepared, preventing the upstreamprofile preparation unit from performing the preparation based on theimproperly-prepared downstream profile.

According to still another aspect, the present invention provides a datastorage medium storing, in a manner readable by a computer, a program ofpreparing an upstream profile and a downstream profile, both of whichare for being used to process image data for recording images on arecording medium, the upstream profile being used for performing a priorprocess onto the image data and the downstream profile being used forperforming a subsequent process on the image data already processed bythe prior process, the program comprising: a program of preparing adownstream profile; a program of preparing an upstream profile using theprepared downstream profile; and a program of judging, after thedownstream profile preparation process and before the upstream profilepreparation process, whether the downstream profile has been properlyprepared, and when it is judged that the downstream profile has beenimproperly prepared, preventing the upstream profile preparation processfrom being performed based on the improperly-prepared downstreamprofile.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the inventionwill become more apparent from reading the following description of theembodiment taken in connection with the accompanying drawings in which:

FIG. 1 is a block drawing showing a profile preparation system accordingto an embodiment of the present invention;

FIG. 2(a) is a flowchart representing an image recording processperformed by using an upstream profile and a downstream profile;

FIG. 2(b) is a schematic view showing color patches printed on arecording medium by the profile preparation system of FIG. 1;

FIG. 3 is a flowchart representing a profile preparation routineperformed by the profile preparation system of FIG. 1;

FIG. 4 is a flowchart representing a modification of the profilepreparation routine;

FIG. 5 is a schematic flow diagram showing an image recording processperformed by using an example of the upstream profile and the downstreamprofile of the present embodiment;

FIG. 6 is a schematic view showing a color correction table used duringthe image recording processes;

FIG. 7 is graph representing a measurement curve, indicative of arelationship between color data and an output density level, and atone-correction curve, indicative of a relationship between color dataand tone-corrected color data, which is represented by a tone correctiontable (upstream profile);

FIG. 8 is a graph representing a relationship between color data, foreach of two basic colors of magenta and cyan, and corresponding lightink data and normal ink data;

FIG. 9(a) is a schematic view showing a light ink conversion tablerepresenting the relationship, between the color data and light inkdata, shown in FIG. 8;

FIG. 9(b) is a schematic view showing a normal ink conversion tablerepresenting the relationship, between the color data and normal inkdata, shown in FIG. 8; and

FIG. 10 is graph representing a measurement curve, indicative of arelationship between ink data and an output density level, and atone-correction curve, indicative of a relationship between ink data andtone-corrected ink data, which is represented by another tone correctiontable (downstream profile).

DETAILED DESCRIPTION OF THE EMBODIMENT

A profile preparation system according to a preferred embodiment of thepresent invention will be described while referring to the accompanyingdrawings.

As shown in FIG. 1, the profile preparation system 100 of the presentembodiment includes a personal computer 1, a color printer 2, and acalorimeter 5. The personal computer 1, the color printer 2, and thecolorimeter 5 are connected together by dedicated interface cables 4, 5for data transmission.

The personal computer 1 includes a CPU 11, a ROM 12, a RAM 13, a harddisk 14, a printer interface 15, a colorimeter interface 19, acathode-ray-tube (CRT) display 16, and an input unit 18, such as a mouseand a keyboard, all connected to a bus 17 for mutual data transmission.

The CPU 11 is for executing various control operations and calculationoperations according to various programs stored in the ROM 12 andaccording to other various programs retrieved from the hard disk 14 andstored in the RAM 13. The ROM 12 stores the various control programs,and also various types of data.

The RAM 13 is capable of storing the various programs retrieved from thehard disk 14, and also various data obtained from calculations performedby the CPU 11.

The hard disk 14 serves as an auxiliary storage unit for storing, asfiles, data and programs which are not stored in main memories such asthe ROM 12 or the RAM 13. More specifically, the hard disk 14 storestherein a profile preparation program for executing a profilepreparation method (FIG. 3). The hard disk 14 further stores therein anupstream profile U and a downstream profile D which are prepared usingthe profile preparation program. The upstream profile U is forcorrecting for changes brought on by passage of time and for uniquecharacteristics of the image recording device 2 itself. The downstreamprofile D is for more precisely correcting for the changes brought on bypassage of time and for the unique characteristics of the imagerecording device 2.

The input unit 18 includes a mouse and a key board, with which a usercan input his/her instruction into the personal computer 1.

The printer interface 15 is for performing two-way data transmissionbetween the computer 1 and the color printer 2 according to a specifictransmission protocol agreed upon by the computer 1 and the colorprinter 2.

The calorimeter interface 19 is for performing two-way data transmissionbetween the computer 1 and the colorimeter 5 according to a specifictransmission protocol agreed upon by the computer 1 and the calorimeter5.

The CRT 16 is for displaying various types of data in a form visuallyrecognizable by the user of the system 100.

The color printer 2 includes an ink-jet type print unit 21 and a PCinterface 22. The print unit 21 is capable of performing datatransmission with the personal computer 1 through the PC interface 22and the printer interface 15.

The print unit 21 is of a type that forms images on a recording mediumby ejecting inks of cyan (C), magenta (M), yellow (Y), and black (K).The print unit 21 can record multi-tone color images, having densitylevels of 256 tones for each of four colors, by selectively ejectingdots of the corresponding ink.

The colorimeter 5 includes a retrieval unit 31 and a PC interface 32.The retrieval unit 31 performs transmission of data with the personalcomputer 1 via the PC interface 32 and the colorimeter interface 19.

The retrieval unit 31 is for measuring the intensity of lighttransmitted through or reflected from an object, dividing the colors ofthe object into three primary colors (RGB), and outputting the densitylevel of each color as a measured color database.

The upstream profile U and the downstream profile D are used during animage recording process for recording images as shown in FIG. 2(a). Theimage recording process of FIG. 2(a) is executed also by the profilepreparation system 100.

During the image recording process, a set of image data for the fourcolors of cyan, magenta, yellow, and black is subjected to a priorprocess in S50. During the prior process, the image data is correctedaccording to the upstream profile U. The image data is then subjected toa subsequent process in S60. During the subsequent process, the imagedata is further corrected according to the downstream profile D. Afterthe subsequent process, the image data is supplied to the printer 2 inS70. As a result, the image data is recorded into a color image. Theupstream and downstream profiles U and D can correct for changes broughton by passage of time and for unique characteristics of the imagerecording device 2 itself. Accordingly, the color image can be recordedin a desirable state by the printer 2.

In order to prepare the upstream and downstream profiles U and D, theprofile preparation system 100 executes the profile preparation program,stored in the hard disk 14, to attain a profile preparation process in amanner shown in FIG. 3.

The profile preparation process of FIG. 3 is started when a user of theprofile preparation system 100 inputs, via the input unit 18, his/herdesire to prepare the upstream profile U and the downstream profile D.The profile preparation process may be executed when the user desires toinitially produce the upstream and downstream profiles. The profilepreparation process may be executed also when the user desires to updatethe upstream and downstream profiles presently stored in the hard disk14. Accordingly, the upstream and downstream profiles U and D can beupdated when the characteristics of the printer 2 changes by the passageof time. The upstream and downstream profiles U and D can be updatedalso when the characteristics of the printer 2 changes for otherreasons. For example, the upstream and downstream profiles U and D canbe updated when the model of the printer 2 is changed, when the type ofimage recording medium used is changed, when the type of ink used ischanged, when the setting of the resolution is changed, or when thesetting of the printing speed is changed.

When the profile preparation process is started, first in S1, the CPU 11stores data of the presently-existing upstream profile and data of thepresently-existing downstream profile. The presently-existing profilesare those that have been prepared prior to the present profilepreparation process and that have been stored in the hard disk 14. Forexample, if the present profile preparation process is executed for thefirst time after the system 100 is purchased, the presently-existingprofiles are those that have been prepared before shipping of the system100. On the other hand, if the present profile preparation process isperformed after the profile preparation process has been performed oneor more times after the system 100 is purchased, the presently-existingprofiles are those that have been prepared by the user of the system 100during a latest-performed profile preparation process. It is noted thatif the present preparation process is executed to initially prepare theprofiles, no profiles are presently existing.

During S1, data of the presently-existing upstream and downstreamprofiles, which are now stored in the hard disk 14, is copied and storedin the RAM 13. Alternatively, a set of back-up data may be created tostore data of the presently-existing profiles, and be stored in somefolder or the like. Thus, data of the presently-existing profiles is noterased or cancelled when the present profile preparation process isstarted. Even when the present profile preparation routine is terminatedin the middle of the process as will be described later, data of thepresently-existing profiles will be restored and can be used thereafter.

Next, in S2, in order to prepare the downstream profile D, the colorprinter 2 is controlled to print color patches on a recording medium.For example, nine cyan color patches are produced by cyan (C) ink asshown in FIG. 2(b) based on image data of predetermined nine tone levelsof 0, 31, 63, 95, 127, 159, 191, 223, and 255. Similarly, nine magentacolor patches are produced by magenta (M) ink based on image data of thepredetermined nine tone levels of 0, 31, 63, 95, 127, 159, 191, 223, and255. Nine yellow color patches are produced by yellow (Y) ink based onimage data of the predetermined nine tone levels of 0, 31, 63, 95, 127,159, 191, 223, and 255. Nine black color patches are produced by black(K) ink based on image data of the predetermined nine tone levels of 0,31, 63, 95, 127, 159, 191, 223, and 255.

Next, in S3, the calorimeter 5 is controlled to measure the densitylevel of the color patches.

Then, in S4, a downstream profile D is prepared based on the results ofmeasurements taken in S3. For example, the downstream profile D isprepared so that input/output characteristic becomes linear for eachcolor.

When the downstream profile D is prepared in S4, the program proceeds toS5.

In S5, the CPU 11 judges whether the present profile preparationprocesses should be terminated. This judgement is performed bycontrolling the CRT display 16 to display a message asking a userwhether or not to terminate the present profile preparation processes.If the user inputs, via the input unit 18, his/her confirmation that thepresent profile preparation processes should be terminated (yes in S5),then the program proceeds to S16. In S16, data of the downstream profileD, which has just been prepared in S4, is restored into the initialstate, which has been stored during S1, and the profile preparationprocesses are ended.

On the other hand, if the present profile preparation processes are tobe continued (S5: NO), then in order to judge the properness of thepresently-prepared downstream profile D and to prepare the upstreamprofile U, the color printer 2 is controlled in S6 to print colorpatches on the recording medium. At this time, for each color, imagedata for the predetermined nine tone levels of 0, 31, 63, 95, 127, 159,191, 223, and 255 is first processed in the same manner as in theprocesses of S60 (FIG. 2(a)) by using the downstream profile D which hasjust been prepared in S4. Then, the printer 2 is controlled by theprocessed image data to print nine color patches. As a result, for eachcolor, nine color patches are produced based on the processed imagedata.

Next, in S7, the calorimeter 5 is controlled to measure the densitylevel of the color patches printed on the recording medium in S6.

Then in S8, the CPU 11 judges whether the prepared downstream profile Dis suitable, based on the results of the measurements made in S7. TheCPU 11 judges whether or not the prepared downstream profile D issuitable by confirming, for each color, whether the measured densitylevels of all the nine color patches increase from one to the next colorpatch in the expected monotone nondecreasing manner. In other words, theCPU 11 judges whether the measured density level of each color patch ishigher than or equal to its preceding color patch. The CPU 11 determinesthat the prepared downstream profile is unsuitable when the measureddensity level of at least one color patch is smaller than its precedingcolor patch. The CPU 11 determines that the prepared downstream profileis suitable when the measured density level of each of all the colorpatches is higher than or equal to its preceding color patch.

Alternatively, the CPU 11 may judge in S8 whether or not the measureddensity level of each color patch is within a predetermined desirablerange for the subject color patch. The CPU 11 determines that theprepared downstream profile is unsuitable when the measured densitylevel of at least one color patch is out of its corresponding desirablerange. The CPU 11 determines that the prepared downstream profile issuitable when the measured density level of each of all the colorpatches is within its corresponding desirable range.

If it is judged in S8 that the prepared downstream profile D isunsuitable (S8: unsuitable), then the program proceeds to S14, in whicha notification is made that the downstream profile has been preparedimproperly. For example, the CRT display 16 is controlled to display amessage that the downstream profile is prepared improperly. Then in S15,the downstream profile D prepared in S4 is restored into the initialstate, which has been stored in S1. Afterward, the routine returns toS2, whereupon the series of processes from preparation of the downstreamprofile D are repeated.

On the other hand, when it is judged that the prepared downstreamprofile D is suitable (S8: suitable), then the program proceeds to S9,in which the upstream profile U is prepared based on the results ofmeasurements taken in S7.

Once the upstream profile U is prepared in S9, then the program proceedsto S10, in which it is again judged whether or not the present profilepreparation processes should be terminated. This process is executed inthe same manner as in S5. If the profile preparation processes should beterminated (S10: YES), then the program proceeds to S16, in which dataof the presently-prepared downstream and upstream profiles U and D isrestored into the initial state, which has been stored in S1. Afterward,the profile preparation processes are ended.

On the other hand, if the profile preparation processes are to becontinued (S10: NO), then in S11 the color printer 2 is controlled toprint test color patches on the recording medium. More specifically, foreach color, image data for the predetermined nine tone values of 0, 31,63, 95, 127, 159, 191, 223, and 255 is first processed in the samemanner as in the process of S50 (FIG. 2(a)) by using the upstreamprofile U, which has just been prepared in S9, and is then processed inthe same manner as in the process of S60 (FIG. 2(a)) by using thedownstream profile D, which has just been prepared in S4. Color patchesare printed based on the image data thus subjected to the processesaccording to both of the upstream and downstream profiles U and D. Thus,nine color patches are printed for each color.

Next, in S12, the calorimeter 5 is controlled to measure the densitylevel of each test color patch printed on the recording medium. In S13,the CPU 11 judges whether the prepared upstream and downstream profilesU and D are suitable based on the results of the measurements taken inS12. The judgment made in S13 is performed in the same manner asdescribed for S8. More specifically, the CPU 11 judges whether or notthe prepared upstream and downstream profiles are suitable byconfirming, for each color, whether or not the measured density levelsof all the nine color patches increase from one to the next color patchin the expected monotone nondecreasing manner. The CPU 11 determinesthat one or both of the prepared upstream and downstream profiles areunsuitable when the measured density level of at least one color patchis smaller than its preceding color patch. The CPU 11 determines thatboth of the prepared upstream and downstream profiles are suitable whenthe measured density level of each of all the color patches is higherthan or equal to its preceding color patch.

Alternatively, the CPU 11 may judge whether the measured density levelof each color patch is within a predetermined desirable range for thesubject color patch. The CPU 11 determines that one or both of theprepared upstream and downstream profiles are unsuitable when themeasured density level of at least one color patch is out of itscorresponding desirable range. The CPU 11 determines that both of theprepared upstream and downstream profiles are suitable when the measureddensity level of each of all the color patches is within itscorresponding desirable range.

If it is judged in S13 that one or both of the upstream and downstreamprofiles is unsuitable (S13: unsuitable), then the program proceeds toS14. In S14, a notification is made that the one or both of the profileshas been prepared improperly. That is, the CRT 16 is controlled todisplay a message that one or both of the profiles has been preparedimproperly. Then the program proceeds to S15, in which data of thedownstream profile D prepared in S4 and data of the upstream profile Uprepared in S9 is restored into the initial state, which has been storedin S1. Afterward, the routine returns to S2, whereupon the series ofprocesses are repeated from preparation of the downstream profile D.

On the other hand, when it is judged that both of the upstream anddownstream profiles are suitable (S13: suitable), then this series ofprofile preparation processes is ended. Then, data of the newly-producedupstream and downstream profiles U and D is written over data of theupstream and downstream profiles already stored in the hard disk 14.Data of the newly-produced upstream and downstream profiles may bestored together with indication data indicating that data of thenewly-produced upstream and downstream profiles should be retrieved andused during an image recording process of FIG. 2(a) to be executed inthe future and during the profile preparation process of FIG. 3 to beexecuted in the future.

It is noted that according to the present embodiment, the process of S13is performed only after it is confirmed in S8 that the downstreamprofile is suitable. Accordingly, if it is judged in S13 that one orboth of the upstream and downstream profiles is unsuitable, thisnormally means that the downstream profile is suitable, but the upstreamprofile is unsuitable. Accordingly, if it is judged in S13 that one orboth of the upstream and downstream profiles is unsuitable, the programmay proceed to S9, rather than to S2, after executing the processes ofS14 and S15. In this case, the series of preparation processes only forthe upstream profile will be repeated.

As described above, according to the profile preparation method of thepresent embodiment, the profile storing process (S1), the downstreamprofile preparation process (S2 to S4), the downstream profile judgmentprocess (S6 to S8), the upstream profile preparation process (S6, S7,S9), and the profile judgment process (S11 to S13) are executed. When itis judged in the downstream profile judgment process that the downstreamprofile has been improperly prepared, or when it is judged in theprofile judgment process that one or both of the upstream and downstreamprofiles has been improperly prepared, then the prepared profile(s) arereturned, in S15, to the initial state of when stored in the profilestoring process (S1). Afterward, the series of processes from preparingthe downstream profile are again executed.

Next will be described one comparative method for preparing the upstreamand downstream profiles U and D.

According to this comparative method, color patches are printed on arecording medium based on several sets of predetermined image data.Then, color of each color patch is measured using the calorimeter 5.Then, the downstream profile D is prepared based on the measurementresults. Next, several sets of predetermined image data are processed inthe same manner as in the subsequent processes of S60 based on thepresently-prepared downstream profile D. Then, color patches arerecorded based on the thus-processed image data. The color of thesepatches is measured using the colorimeter 5. Then, the upstream profileU is prepared based on the measurement results.

According to this comparative method, the downstream and upstreamprofiles D and U are prepared consecutively. Judgement of whether thedownstream and upstream profiles are unsuitable is performed after bothof the downstream and upstream profiles are prepared. That is, judgementof whether the downstream and upstream profiles are suitable isperformed only when the image recording process of FIG. 2(a) is executedto actually use the profiles.

Thus, according to this comparative method, the upstream profile U isalways prepared based on the downstream profile D, even when thedownstream profile D is prepared inappropriate. In this case, theupstream profile U is also prepared improperly. Therefore, it isimpossible to efficiently prepare the interrelated upstream anddownstream profiles U and D. Judgement of properness of the profiles isnot performed during the profile preparation processes. The only way tocheck whether profiles have been properly prepared is by actuallyoutputting an image in the normal use mode of FIG. 2(a) after profilepreparation processes are completely finished. If the profiles areunsuitable, then the profile preparation processes need to be performedagain. This makes it troublesome to prepare proper profiles.

Contrarily, according to the present embodiment, the judgment aboutwhether the prepared downstream profile is suitable or not is made afterthe downstream profile is prepared, but before the upstream profile isprepared. When the downstream profile is improperly prepared, then thedownstream profile is promptly prepared again, without preparing theupstream profile, which is to be influenced by the downstream profile.Therefore, even if the downstream profile is improperly prepared, theprofiles can be more efficiently prepared than the comparative manner,wherein the upstream profile is prepared whenever the downstream profileis prepared.

The profile preparation system 100 is designed so that after theupstream profile is prepared, it can be judged whether the preparedupstream and downstream profiles are properly prepared. With thisconfiguration, if at least one of the upstream and downstream profileshas not been properly prepared, then the profile preparation processeswill be promptly restarted. The upstream and downstream profiles can beprepared more efficiently, with less trouble, than when using thecomparative profile preparation method, wherein whether a profile isproperly prepared can only be judged by actually outputting an imageusing a normal usage mode of FIG. 2(a).

Also, because data of the upstream and downstream profiles, which existbefore the profiles are newly prepared, are stored in S1, even if theprofiles are not properly prepared, or if profile preparation processesare terminated in the middle of the processes, the profiles can bepromptly returned to the initial condition, so that it is ensured thatimages can be recorded using the initial condition profiles.

The profile preparation method of the present embodiment will bedescribed below in greater detail with reference to a specific exampleof the upstream profile U and a specific example of the downstreamprofile D.

The specific example of the upstream profile U and the specific exampleof the downstream profile D are used in the image recording process ofFIG. 5. It is noted that the image recording process of FIG. 5 isexecuted also by the profile preparation system 100 of the presentembodiment.

During the image recording process of FIG. 5, when input color data (Ci,Mi, Yi, Ki) is received from an image preparation application or thelike, the input image data (Ci, Mi, Yi, Ki) is color-corrected in S100into color-corrected color data (Ci′, Mi′, Yi′, Ki′) by using acolor-correction table T1.

Then, in S200, the cyan component Ci′ of the color-corrected color data(Ci′, Mi′, Yi′, Ki′) is tone-corrected into color-and-tone-correctedcyan data Ci″ by using a tone-correction table T2 c for cyan color. Themagenta component Mi′ is tone-corrected into color-and-tone-correctedmagenta data Mi″ by using a tone-correction table T2 m for magentacolor. The yellow component Yi′ is tone-corrected intocolor-and-tone-corrected yellow data Yi″ by using a tone-correctiontable T2 y for yellow color. The black component Ki′ is tone-correctedinto color-and-tone-corrected black data Ki″ by using a tone-correctiontable T2 k for yellow color.

Then, in S300, the color-and-tone-corrected cyan data Ci″ is convertedinto light cyan ink data Cl and normal cyan ink data Cn by using a cyanconversion table T3 c. The color-and-tone-corrected magenta data Mi″ isconverted into light magenta ink data Ml and normal magenta ink data Mnby using a magenta conversion table T3 m.

Then, in S400, the light cyan ink data Cl is tone-corrected intotone-corrected light cyan ink data Cl′ by using a tone-correction tableT4 c 1 for light cyan ink. The normal cyan ink data Cn is tone-correctedinto tone-corrected normal cyan ink data Cn′ by using a tone-correctiontable T4 cn for normal cyan ink. The light magenta ink data Ml istone-corrected into tone-corrected light magenta ink data Ml′ by using atone-correction table T4 ml for light magenta ink. The normal magentaink data Mn is tone-corrected into tone-corrected normal magenta inkdata Mn by using a tone-correction table T4 nm for normal magenta ink.

Then, in S500, the tone-corrected ink data Cl′, Cn′, Ml′, Mn′ for lightcyan, normal cyan, light magenta, and normal magenta, and thecolor-and-tone-corrected data Yi″ and Ki″ for yellow and black arebinarized into a set of binarized color data (Clo, Cno, Mlo, Mno, Yo,Ko) in a well-known manner, such as described in U.S. Pat. No.5,045,952.

Then, in S600, the binarized color data (Clo, Cno, Mlo, Mno, Yo, Ko) isoutputted to the printer 2, where a desired color image is printed basedon the binarized color data (Clo, Cno, Mlo, Mno, Yo, Ko).

In this example, the print unit 21 is of a type that forms images on arecording medium by ejecting six inks of light cyan (Cl), normal cyan(Cn), light magenta (Ml), normal magenta (Mn), yellow (Y), and black (K)based on a set of binary color data (Clo, Cno, Mlo, Mno, Yo, Ko) that isreceived from the personal computer 1. It is noted that the normal cyanink has cyan color denser than the light cyan ink. Similarly, the normalmagenta ink has magenta color denser than the light magenta ink. Theprint unit 21 is configured to record multi-tone color images, havingdensity levels of 256 different tones for each of four colors of cyan,magenta, yellow, and black, by selectively ejecting dots of the six inksaccording to the binary color data (Clo, Cno, Mlo, Mno, Yo, Ko).

It is noted that the tone-correction tables T2 c, T2 m, T2 y, and T2 kare the example of the upstream profile U. The tone-correction tables T4cl, T4 cn, T4 ml, and T4 nm are the example of the downstream profile D.The tables T1, T2 c, T2 m, T2 y, and T2 k, T3 c and T3 m, and T4 cl, T4cn, T4 ml, and T4 nm are stored in the hard disk 14.

The color correction table T1 is a look up table used to correct, inS100, input color data (Ci, Mi, Yi, Ki) in order to reproduce colorsfaithfully by taking into account how respective colors of cyan,magenta, yellow, and black influence one another. As shown in FIG. 6,the color correction table T1 includes a plurality of sets of color data(C, M, Y, K), which are possibly inputtable to the color-correctionprocess of S100. The color correction table T1 includes, incorrespondence with each set of color data (C, M, Y, K), a set ofcolor-corrected color data (C′, M′, Y′, K′), which should be outputtedfrom the color-correction process of S100 in response to the input ofthe subject set of color data (C, M, Y, K).

More specifically, the color correction table T1 includes 6,561 (=9⁴)sets of color data (C, M, Y, K), wherein C=0, 31, 63, 95, 127, 159, 191,223, and 255, M=0, 31, 63, 95, 127, 159, 191, 223, and 255, Y=0, 31, 63,95, 127, 159, 191, 223, and 255, and K=0, 31, 63, 95, 127, 159, 191,223, and 255. In association with each set of color data (C, M, Y, K),the table T1 includes one set of color-corrected color data (C′, M′, Y′,K′) that should be outputted from the process of S100 to reproduce thecorresponding color data (C, M, Y, K). Thus, the color correction tableT1 is configured as a four-dimensional look up table, in which 6,561sets of color-correction data (C′, M′, Y′, K′) are stored in one to onecorrespondence with the 6,561 sets of color data (C, M, Y, K).

The tone-correction tables T2 c, T2 m, T2 y, and T2 k are provided asthe upstream profile U used to correct for changes brought on by passageof time and for unique characteristics of the image recording device 2itself.

The tone correction tables T2 c, T2 m, T2 y, and T2 k are provided inone to one correspondence with the four colors of cyan (C), magenta (M),yellow (Y), and black (K). A tone correction table T2 a (a=c, m, y, ork) for each color component, is used to correct, in S200, the tone Ai′(=Ci′, Mi′, Yi′, or Ki′) of the corresponding color component in theinput color data (Ci′, Mi′, Yi′, Ki′), which has already beencolor-corrected in S100, into a color-and-tone-corrected value Ai″(=Ci″, Mi″, Yi″ or Ki″) so that processes of S200 through S600 willattain a linear “tone characteristic”. It is noted that the “tonecharacteristic” is defined as the density level of an image, to beactually outputted on the recording medium in S600, with respect to thecolor-corrected tone value Ai′ (=Ci′, Mi′, Yi′, or Ki′). The outputdensity is determined by actually measuring the output image using thecolorimeter 5.

It is assumed that when the cyan color component Ci′ of color-correctedcolor data (Ci′, Mi′, Yi′, Ki′) from S100 is subjected to the processesof S200-S600, an output density level is obtained in S600 as indicatedby a one-dot-and-one-chain line in FIG. 7. In this case, the tonecorrection table T2 c should be prepared to produce an input/outputcharacteristic correction curve, as indicated by a broken line in thefigure, to correct for the cyan tone Ci′ of the color-corrected colordata and to attain a linear input/output characteristic, as indicated bya solid, straight line in the figure.

Accordingly, the tone correction table T2 a (a=c, m, y, or k) for eachcolor component A (=C, M, Y, or K) is prepared to include a plurality ofsets of color-corrected data A′ (=C′, M′, Y′, or K′), which areoutputtable from the color-correction process of S100 and are thereforeinputtable to the tone-correction process of S200. The tone correctiontable T2 a (a=c, m, y, or k) includes, in correspondence with each setof color-corrected data A′ (=C′, M′, Y′, or K′), a set ofcolor-and-tone-corrected data A″ (=C″, M″, Y″, or K″), which should beoutputted from the tone-correction process of S200 in response to inputof the subject set of color-corrected data A′ (=C′, M′, Y′, or K′).

The tone correction table T2 a (a=c, m, y, or k) stores a set ofcolor-and-tone-corrected color data A″ (=C″, M″, Y″, or K″) for each ofa plurality of sets of color-corrected color data A′ (=C′, M′, Y′, orK′), which are arranged at a fixed interval. For example, the tonecorrection table T2 a (a=c, m, y, or k) stores a set ofcolor-and-tone-corrected color data A″ (=C″, M″, Y″, or K″) for each ofall the 256 sets of color-corrected color data A′ (=C′, M′, Y′, or K′)of 0 to 255.

The conversion tables T3 c and T3 m are provided in one to onecorrespondence with cyan and magenta colors, each of which is expressedusing corresponding light ink and corresponding normal ink. Eachconversion table T3 a (a=c or m) is used to divide, in S300, color dataAi″ (=Ci″ or Mi″), which has already been color-corrected in S100 andtone-corrected in S200, into light ink data Al (=Cl or Ml) and normalink data An (=Cn or Mn) in a conversion characteristic shown in FIG. 8.

The cyan conversion table T3 c is comprised from a light cyan conversiontable T3 cl and a normal cyan conversion table T3 cn. The magentaconversion table T3 m is comprised from a light magenta conversion tableT3 ml and a normal magenta conversion table T3 nm. For each of cyan andmagenta colors, the light ink conversion table T3 al (a=c or m) and thenormal ink conversion table T3 an (a=c or m) are prepared as shown inFIGS. 9 (a) and 9 (b) to represent the conversion characteristic of FIG.8.

Each of the conversion tables T3 an and T3 al (a=c or m) includes aplurality of sets of color-and-tone-corrected data A″ (=C″ or M″), whichare outputtable from the tone-correction process of S200 and aretherefore inputtable to the conversion process of S300. The light inkconversion table T3 al (a=c or m) includes, in correspondence with eachset of color-and-tone-corrected data A″ (=C″ or M″), a set of light inkdata B (=Cl or Ml), which should be outputted from the conversionprocess of S300 in response to input of the subject set ofcolor-and-tone-corrected data A″ (=C″ or M″). The normal ink conversiontable T3 an (a=c or m) includes, in correspondence with each set ofcolor-and-tone-corrected data A″ (=C″ or M″), a set of normal ink data B(=Cn or Mn), which should be outputted from the conversion process ofS300 in response to input of the subject set of color-and-tone-correcteddata A″ (=C″ or M″).

It is noted that according to the conversion characteristic of FIG. 8,in order to reproduce each of cyan and magenta colors, when the tonevalue of the color-and-tone-corrected data A″ (=C″ or M″) is smallerthan a predetermined reference tone value (127, for example), only lightink is used to reproduce the tone by changing the dot recording densityof light ink. Normal ink starts being used when the tone value of thecolor-and-tone-corrected data A″ (=C″ or M″) reaches the reference tonevalue (127). Once the reference tone value is reached, the tone isreproduced by gradually (linearly) reducing the dot recording density oflight ink while gradually (linearly) increasing the dot recordingdensity of normal ink in association with increase in the tone value ofthe color-and-tone-corrected data A″ (=C″ or M″).

The tone-correction tables T4 cl, T4 cn, T4 ml, and T4 nm are providedas the downstream profile D used to more precisely correct for changesbrought on by passage of time and for unique characteristics of theimage recording device 2 itself, than the tone-correction tables T2 cand T2 m.

The tone correction tables T4 cl, T4 cn, T4 ml, and T4 nm are providedin one to one correspondence with the four inks of light cyan (Cl),normal cyan (Cn), light magenta (Ml), and normal magenta (Mn). A tonecorrection table T4 b (b=cl, cn, ml, or mn) for each ink, is used tocorrect, in S400, ink data B (=Cl, Cn, Ml, or Mn), which has beenobtained in S300, into a tone-corrected ink data B′ (=Cl′, Cn′, Ml′, orMn′) so that processes of S400 through S600 will attain a linear “tonecharacteristic”. It is noted that the “tone characteristic” is definedas the density level of an image, to be actually outputted on therecording medium in S600, with respect to the ink data B (=Cl, Cn, Ml,or Mn). The output density is determined by actually measuring theoutput image using the colorimeter 5.

It is assumed that when light cyan ink data Cl from S300 is subjected tothe processes of S400-S600, an output density level is obtained in S600as indicated by a one-dot-and-one-chain line in FIG. 10. In this case,the tone correction table T4 cl should be prepared to produce aninput/output characteristic correction curve, as indicated by a brokenline in the figure, to correct for the light cyan value Cl and to attaina linear input/output characteristic, as indicated by a solid, straightline in the figure.

Accordingly, the tone correction table T4 b (b=cl, cn, ml, or mn) isprepared to include a plurality of sets of ink data B (=Cl, Cn, Ml, orMn), which are outputtable from the conversion process of S300 and aretherefore inputtable to the tone-correction process of S400. The tonecorrection table T4 b (b=cl, cn, ml, or mn) includes, in correspondencewith each set of ink data B (=Cl, Cn, Ml, or Mn), a set oftone-corrected data B′ (=Cl′, Cn′, Ml′, or Mn′), which should beoutputted from the tone-correction process of S400 in response to inputof the subject set of ink data B (=Cl, Cn, Ml, or Mn).

The tone correction table T4 b (b=cl, cn, ml, or mn) stores a set oftone-corrected ink data B′ (=Cl′, Cn′, Ml′, or Mn′) for each of aplurality of sets of ink data B (=Cl, Cn, Ml, or Mn) which are arrangedat a fixed interval. For example, the tone correction table T4 b (b=cl,cn, ml, or nm) stores a set of tone-corrected ink data B′ (=Cl′, Cn′,Ml′, or Mn′) for each of all the 256 sets of ink data B (=Cl, Cn, Ml, orMn) of 0 to 255.

Data of the color-correction table T1, the conversion tables T3 cl, T3cn, T3 ml, and T3 nm, the tone-correction tables T2 c, T2 m, T2 y, andT2 k (upstream profile U), and the tone-correction tables T4 cl, T4 cn,T4 ml, and T4 nm (downstream profile D) are produced in advance, andstored in the hard disk 14.

Next will be described how to produce the color correction table T1, thetone correction tables T2 c, T2 m, T2 y, and T2 k, the conversion tablesT3 cl, T3 cn, T3 ml and T3 nm, and the tone correction tables T4 cl, T4cn, T4 ml, and T4 nm. It is noted that the tone correction tables T4 b(b=cl, cn, ml, and mn), the conversion tables T3 al and T3 an (a c andm), the tone correction tables T2 a (a=c, m, y, and k), and the colorcorrection table T1 are prepared in this order.

First will be described how to prepare the tone correction table T4 clfor light cyan ink.

It is noted that the tone correction tables T4 cn, T4 ml, and T4 nm areprepared for normal cyan ink, light magenta ink, and normal magenta inkin the same manner as described below for light cyan ink.

First, nine sets of light cyan ink data Cl of 0, 31, 63, 95, 127, 159,191, 223, and 255, which will be possibly inputted into thetone-correction process of S400, are prepared. Each set of ink data Clis subjected to no tone-correction process of S400. As a result, ninesets of ink data Cl′ having the same tone values 0, 31, 63, 95, 127,159, 191, 223, and 255 are obtained.

Then, the print unit 21 is controlled by the nine sets of light cyan inkdata Cl′ to print nine single-color color patches on a recording mediumusing light cyan ink. That is, each set of ink data Cl′ is binarized inthe same manner as in the process of S500, and supplied to the printer2. As a result, nine color patches are produced as shown in FIG. 2(b).Then, the output density level of each color patch is measured using thecolorimeter 5.

A graph of FIG. 10 is then prepared, in which the horizontal axisindicates ink data Cl in the range of 0-255, a left-hand vertical axisindicates the measured density levels in the range of 0-255, and aright-hand vertical axis indicates tone-corrected levels Cl′ of 0-255 tobe obtained. Based on the measurement results of the nine color patches,a measurement curve is prepared, as indicated by a one-dot-and-one-chainline in the figure, to represent the relationship between the ink dataCl (horizontal axis) and the measured density values (left-hand verticalaxis). A predetermined reference line is then plotted in the same graphto connect the minimum tone point (0, 0) and the maximum tone point(255, 255) as indicated by a solid line in the figure. Then, asindicated by a broken line in the same figure, a tone-correction curveis calculated as a curve that is symmetrical to the measurement curvewith respect to the reference line. The tone-correction curve is thenset as a tone-correction table T4 cl. That is, along the tone-correctioncurve, the value of tone-corrected data Cl′, defined along theright-hand vertical axis, is determined for each of a plurality ofvalues of ink data Cl, defined along the horizontal axis.

It is noted that the measurement results of the color patches show thatwhen ink data Cl is subjected to the color reproducing characteristic ofS500-S600, represented by the measurement curve (one-dot-and-one-chainline in FIG. 10), the ink data Cl is converted into the output densitylevel plotted on the measurement curve. The tone-correction curve(broken line in FIG. 10) is therefore determined so that when any inkdata Cl is actually inputted, the ink data Cl will be subjected first tothe tone correction characteristic of S400, represented by thetone-correction curve, and then to the color reproducing characteristicof S500-S600, represented by the measurement curve, resulting in theoutput density levels on the linear reference line. Accordingly,actually-inputted color data Cl will be converted through S400-S600 tothe output density levels with a linear conversion characteristic, whichis a combination of the tone correction characteristic of S400,represented by the tone-correction curve (broken line in FIG. 10), andthe color reproducing characteristic of S500-S600, represented by themeasurement curve (one-dot-and-one-chain line in FIG. 10).

Next will be described how to prepare the conversion tables T3 cn and T3cl for cyan color. It is noted that the conversion tables T3 nm and T3ml for magenta color are prepared in the same manner as described belowfor cyan color.

First, the reference tone value is set to a desirable value (“127,” inthis example). The reference tone value is defined as a tone level pointC″, from which normal ink will be used.

Next, the value of normal ink data Cn for the reference tone value C″ of127 is determined as a desirable value (“1,” for example). This valueindicates the amount of normal ink that should be ejected, together withlight ink, to reproduce the reference tone value C″ of 127.

Then, the value of light ink data Cl for the reference tone value C″ of127 is determined in a trial-and-error manner described below. It isnoted that this value indicates the amount of light ink that should beejected, together with normal ink, to reproduce the reference tone valueC″ of 127.

First, the print unit 21 is controlled to produce a plurality ofsingle-color color patches by ejecting light ink on a recording mediumbased on a plurality of tone levels that differ from one another instepwise increments. More specifically, a plurality of sets of light inkdata Cl are prepared so that the plurality of sets of ink data have aplurality of tone levels that are different from one another in stepwiseincrements. The plural sets of ink data are tone-corrected in the samemanner as in the process of S400 by using the table T4 cl, which hasbeen already prepared for light cyan ink, binarized in the same manneras in the process of S500, and supplied to the printer 2. As a result,the plurality of single-color color patches are produced by light cyanink in stepwisely-increasing dot recording densities.

Then, the print unit 21 is controlled to eject normal ink, onto eachsingle-color color patch, based on the tone level (‘1’ in this example)that is already determined for the reference tone level C″ of 127. Morespecifically, one set of normal ink data Cn of 1 is prepared,tone-corrected in the same manner as in the process of S400 by using thetable T4 cn, binarized in the same manner as in the process of S500, andsupplied to the printer 2. As a result, each single-color color patch isfurther printed with normal ink at a dot recording density thatcorresponds to the tone level of “1”.

Then, the plurality of single-color color patches are visually observedby an operator to select one or more allowable color patches wherenormal ink dot “roughness” appear unnoticeable. Then, one color patch isselected that has been printed with the lowest tone level of light inkamong the selected one or more allowable color patches. The tone levelof the thus selected one color patch is determined as the lowestallowable light ink amount for the reference tone level C″ of 127.

The print unit 21 is further controlled to produce a plurality ofmixed-color color patches by ejecting four inks of: light cyan ink,light magenta ink, yellow ink, and black ink, at a plurality of tonelevels that are different from one another in stepwise increments. Eachcolor patch is produced according to the same tone level for all of thefour inks. More specifically, a plurality of sets of color data (Cl, Ml,Y″, K″) are prepared. The plurality of sets of color data have aplurality of tone levels that are different from one another in stepwiseincrements. Each data set has the same tone value for all the four colorcomponents Cl, Ml, Y″, and K″. The yellow and black components Y″ and K″are binarized in the same manner as in the process of S500, and suppliedto the printer 2. The cyan and magenta components Cl and Ml aretone-corrected in the same manner as in the processes of S400 by usingthe tables T4 cl and T4 ml, binarized in the same manner as in theprocess of S500, and supplied to the printer 2. As a result, a pluralityof mixed-color color patches are produced by all the four inks instepwisely-increasing dot recording densities.

Then, the plurality of mixed-color color patches are visually observedby the operator to select one or more allowable color patches where nobleeding appear in cyan or magenta light ink. One color patch is thenselected that has printed with the highest tone level among the selectedone or more allowable color patches. The tone level of the thus selectedone color patch is determined as the highest allowable light ink amountfor the reference tone level C″ of 127.

When the thus determined highest allowable light ink amount is equal tothe determined lowest allowable light ink amount, the highest or lowestallowable light ink amount is determined as light ink tone data Cl thatshould be outputted in S300 for the reference tone level C″ of 127.Accordingly, the highest or lowest allowable light ink amount isdetermined as light ink data Cl for the reference tone C″ of 127. Inthis example, as shown in FIGS. 8 and 9(a), light ink data Cl isdetermined as “255” with respect to the reference tone value C″ of 127.

On the other hand, when the determined highest and lowest allowablelight ink amounts are not equal to each other, observations of thesingle-color color patches and of the mixed-color color patches areperformed again to reselect allowable color patches in a lower precisionso that the lowest and highest allowable light ink amounts will becomeequal to each other.

Next, the value of light ink data Cl is determined for all the remainingtone values C″ of 0-126 and 128-255.

First, the value of light ink data Cl is determined as “0” for colordata C″ of the minimum and maximum tone values of 0 and 255. Then, asshown in FIG. 8, a graph is prepared in which the horizontal axisdenotes color data C″ in the range of 0 to 255, and the vertical axisdenotes light ink data and normal ink data both in the range of 0 to255. Then, as indicated by a broken line in FIG. 8, a linearlyincreasing-and-then-decreasing line is prepared to connect the light inkminimum-tone point (0, 0) to the light ink reference-tone point (127,255) and further to the light ink maximum-tone point (255, 0). Alongthis linearly increasing-and-decreasing line, the value of light inkdata Cl, defined along the vertical axis, is determined for all of the256 color data C″ of 0, 1, . . . , 255 defined along the horizontalaxis. As a result, light ink data Cl is determined as shown in FIG. 9(a)with respect to all of the tone values of 0-255 of color data C″.

Next, the value of normal ink data is determined for all of theremaining tone values of 0-126 and 128-255 of color data C″ in atrial-and-error manner described below. It is noted that the value ofnormal ink data Cn is already determined as “1”, for the reference tonevalue C″ of 127.

First, the value of normal ink data Cn is determined as “0” for all thetone values C″ of 0-126 that are smaller than the reference tone value127.

Then, the value of normal ink data is determined for the maximum tonevalue C″ of 255 in a manner described below.

First, the print unit 21 is controlled to produce a plurality ofsingle-color color patches by ejecting normal ink on a recording mediumbased on a plurality of tone levels that differ from one another instepwise increments. More specifically, a plurality of sets of normalink data Cn are prepared so that the plurality of sets of ink data havea plurality of tone levels that are different from one another instepwise increments. The plural sets of ink data are tone-corrected inthe same manner as in the processes of S400 by using the table T4 cn,binarized in the same manner as in the process of S500, and supplied tothe printer 2. As a result, the plurality of single-color color patchesare produced by normal ink in stepwisely-increasing dot recordingdensities.

Then, the print unit 21 is controlled to eject light ink, onto eachsingle-color color patch, based on the tone level of light ink that isalready determined for the maximum tone level C″ of 255. In thisexample, the tone level is already determined as “0” for the maximumtone level C″ of 255. Accordingly, one set of light ink data Cl of “0”is prepared, tone-corrected in the same manner as in the process of S400by using the table T4 cl, binarized in the same manner as in the processof S500, and supplied to the printer 2.

Then, the plurality of single-color color patches are visually observedby the operator to select one or more allowable color patches where noundesirable white regions appear noticeable. One color patch is thenselected that has printed with the lowest tone level of normal ink amongthe selected one or more allowable color patches. The tone level of thiscolor patch is determined as the lowest allowable normal ink amount forthe maximum tone level C″ of 255.

Next, the print unit 21 is controlled to produce a plurality ofmixed-color color patches by ejecting four inks of: normal cyan ink,normal magenta ink, yellow ink, and black ink, at a plurality of tonelevels that are different from one another in stepwise increments. Eachcolor patch is produced according to the same tone level for all of thefour inks. More specifically, a plurality of sets of color data (Cn, Mn,Y″, K″) are prepared. The plurality of sets of color data have aplurality of tone levels that are different from one another in stepwiseincrements. Each data set has the same tone value for all the four colorcomponents Cn, Mn, Y″, and K″. The yellow and black components Y″ and K″are binarized in the same manner as in the process of S500, and suppliedto the printer 2. The cyan and magenta components Cn and Mn aretone-corrected in the same manner as in the processes of S400 by usingthe tables T4 cn and T4 nm, binarized in the same manner as in theprocess of S500, and supplied to the printer 2. As a result, theplurality of mixed-color color patches are produced by the four inks instepwisely-increasing dot recording densities.

Then, the plurality of mixed-color color patches are visually observedby the operator to select one or more allowable color patches where nobleeding or blurring appear in the cyan or magenta normal ink. One colorpatch is then selected that has printed with the highest tone levelamong the selected one or more allowable color patches. The tone levelof the thus selected one color patch is determined as the highestallowable normal ink amount for the maximum tone level C″ of 255.

When the thus determined highest allowable normal ink amount is equal tothe determined lowest allowable normal ink amount, the highest or lowestallowable normal ink amount is determined as normal ink tone data Cnthat should be outputted from S300 for the maximum tone level C″ of 255.Accordingly, the highest or lowest allowable normal ink amount isdetermined as normal ink data Cn for the maximum tone C″ of 255. In thisexample, as shown in FIGS. 8 and 9(b), normal ink data Cn is determinedas “255” with respect to the maximum tone value C″ of 255.

On the other hand, when the determined highest and lowest allowablenormal ink amounts are not equal to each other, observations of thesingle-color color patches and of the mixed-color color patches areperformed again to reselect allowable color patches in a lower precisionso that the lowest and highest allowable normal ink amounts will becomeequal to each other.

Next, the value of normal ink data Cn is determined for all theremaining tone values C″ of 128-254.

As indicated by a solid line in FIG. 8, a linearly increasing line isproduced to connect the normal ink reference-tone point (127, 1) to thenormal ink maximum-tone point (255, 255). Along this linearly-increasingline, the value of normal ink data Cn, defined along the vertical axis,is determined for each of all the values of color data C″ of 128, 129,130, . . . , 253, and 254, defined along the horizontal axis. Thus, thevalue of normal ink data Cn with respect to all the tone values C″ of127-255 is determined and stored as shown in FIG. 9(b).

Next will be described how to prepare the tone correction table T2 c forcyan color. It is noted that the tone correction table T2 m is preparedfor magenta color in the same manner as described below for cyan color.

First, nine sets of color data C′ of 0, 31, 63, 95, 127, 159, 191, 223,and 255 which will be possibly inputted into the tone-correction processof S200, are prepared. Each set of color data C′ is subjected to notone-correction process of S200. As a result, nine sets of color data C″having the tone values 0, 31, 63, 95, 127, 159, 191, 223, and 255 areobtained. Then, the nine sets of color data C″ are subjected to theconversion process of S300. As a result, each set of color data C″ isconverted into normal ink data Cn and light ink data Cl by using theconversion tables T3 cn and T3 cl, which have already been produced.Thus, nine sets of color data C′ are directly converted into nine setsof ink data (Cn, Cl). Then, the nine sets of ink data (Cn, Cl) aresubjected to the tone-correction process of S400. As a result, each setof ink data (Cn, Cl) is tone-corrected into a set of tone-corrected inkdata (Cn′, Cl′) by using the tone-correction tables T4 cn and T4 cl,which have already been produced. Thus, the nine sets of ink data (Cn,Cl) are tone-corrected into nine sets of ink data (Cn′, Cl′).

Then, the print unit 21 is controlled by the nine sets of ink data (Cn′,Cl′) to print nine single-color color patches on a recording mediumusing both light and normal inks. That is, each set of ink data (Cn′,Cl′) is binarized in the same manner as in the process of S500, andsupplied to the printer 2. As a result, nine color patches are producedas shown in FIG. 2(b). Then, the output density level of each colorpatch is measured using the colorimeter 5.

A graph of FIG. 7 is then prepared, in which the horizontal axisindicates color data C′ in the range of 0-255, a left-hand vertical axisindicates the measured density levels in the range of 0-255, and aright-hand vertical axis indicates tone-corrected levels C″ of 0-255 tobe obtained. Based on the measurement results of the nine color patches,a measurement curve is prepared, as indicated by a one-dot-and-one-chainline in the figure, to represent the relationship between the color dataC′ (horizontal axis) and the measured density values (left-hand verticalaxis). A predetermined reference line is then plotted in the same graphto connect the minimum tone point (0, 0) and the maximum tone point(255, 255) as indicated by a solid line in the figure. Then, asindicated by a broken line in the same figure, a tone-correction curveis calculated as a curve that is symmetrical to the measurement curvewith respect to the reference line. The tone-correction curve is thenset as a tone-correction table T2 c. That is, along the tone-correctioncurve, the value of tone-corrected data C″, defined along the right-handvertical axis, is determined for each of a plurality of values of colordata C′, defined along the horizontal axis.

It is noted that the measurement results of the color patches show thatwhen color data C′ is subjected to the color reproducing characteristicof S300-S600, represented by the measurement curve(one-dot-and-one-chain line in FIG. 7), the color data C′ is convertedinto the output density level plotted on the measurement curve. Thetone-correction curve (broken line in FIG. 7) is therefore determined sothat when any color data C′ is actually inputted, the color data C′ willbe subjected first to the tone correction characteristic of S200,represented by the tone-correction curve, and then to the colorreproducing characteristic of S300-S600, represented by the measurementcurve, resulting in the output density levels on the linear referenceline. Accordingly, actually-inputted color data C′ will be convertedthrough S200-S600 to the output density levels with a linear conversioncharacteristic, which is a combination of the tone correctioncharacteristic of S200, represented by the tone-correction curve (brokenline in FIG. 7), and the color reproducing characteristic of S300-S600,represented by the measurement curve (one-dot-and-one-chain line in FIG.7).

Next will be described how to prepare the tone correction table T2 y foryellow color. It is noted that the tone correction table T2 k isprepared for black color in the same manner as described below foryellow color.

The print unit 21 is first controlled according to nine sets of colordata Y′ of 0, 31, 63, 95, 127, 159, 191, 223, and 255 to produce ninecolor patches. More specifically, nine sets of yellow color data Y′ of0, 31, 63, 95, 127, 159, 191, 223, and 255 are prepared, binarized inthe same manner as in the process of S500, and are supplied to theprinter 2. As a result, nine color patches are produced by yellow ink asshown in FIG. 2(b). Densities of the nine color patches are measured bythe calorimeter 5. As a result, a measurement curve(one-dot-and-one-chain line) of FIG. 7 is produced based on themeasurement results similarly as described above for cyan ink. Apredetermined reference line (solid line) and a tone-correction curve(broken line) are determined also in the same manner as described above.The thus obtained tone-correction curve (broken line) is set as thetone-correction table T2 y for the yellow color.

Next will be described how to prepare the color-correction table T1.

First, 6,561 (=9⁴) sets of color data (C′, M′, Y′, K′), which willpossibly be outputted from the color-correction process of S100, areprepared, wherein C=0, 31, 63, 95, 127, 159, 191, 223, and 255, M=0, 31,63, 95, 127, 159, 191, 223, and 255, Y=0, 31, 63, 95, 127, 159, 191,223, and 255, and K=0, 31, 63, 95, 127, 159, 191, 223, and 255. Theyellow component Y′ of each set of color data (C′, M′, Y′, K′) istone-corrected into tone-corrected data Y″ in the same manner as in theprocess of S200 using the tone-correction table T2 y already preparedfor yellow color in the manner described above. Similarly, the blackcomponent K′ of each set of color data (C′, M′, Y′, K′) istone-corrected into tone-corrected data K″ in the same manner as in theprocess of S200 using the tone-correction table T2 k already preparedfor black color. The cyan component C′ of each set of color data (C′,M′, Y′, K′) is tone-corrected into tone-corrected data C″ in the samemanner as in the process of S200 using the tone-correction table T2 calready prepared for cyan color, converted in the same manner as in theprocess of S300 into light ink data Cl and normal ink data Cn using theconversion tables T3 cl and T3 cn already prepared for cyan color, andare tone-corrected in the same manner as in the process of S400 intotone-corrected ink data Cl′ and Cn′ using the tone-correction tables T4cl and T4 cn already prepared for cyan color. Similarly, the magentacomponent M′ of each set of color data (C′, M′, Y′, K′) istone-corrected into tone-corrected data M″ in the same manner as in theprocess of S200 using the tone-correction table T2 m already preparedfor magenta color, converted in the same manner as in the process ofS300 into light ink data Ml and normal ink data Mn using the conversiontables T3 ml and T3 nm already prepared for magenta color, and aretone-corrected in the same manner as in the process of S400 intotone-corrected ink data Ml′ and Mn′ using the tone-correction tables T4ml and T4 nm already prepared for magenta color. Thus, each set of colordata (C′, M′, Y′, K′) is converted into a set of color data (Cl′, Cn′,Ml′, Mn′, Y″, K″). The set of color data (Cl′, Cn′, Ml′, Mn′, Y″, K″) isthen binarized into binarized data (Clo, Cno, Mlo, Mno, Yo, Ko) in thesame manner as in the process of S500, and is supplied to the printer 2.As a result, the print unit 21 is controlled to produce 6,561 colorpatches.

The color patches are measured using the colorimeter 5 in order todetermine L*a*b* color values (L, a, b), defined in the L*a*b*calorimetric system (CIE 1976), for all the sets of original color data(C′, M′, Y′, K′). Interpolation calculation is performed on the measuredL*a*b* color values and the original color values (C′, M′, Y′, K′) todetermine a relationship between a plurality of Lab color values (L, a,b) and a plurality of color values (C′, M′, Y′, K′), which are to beoutputted from the color-correction process of Next, the relationshipbetween color values (C, M, Y, K), which are inputtable to the colorcorrection process of S100, and L*a*b* color values (L, a, b) isdetermined. More specifically, 6,561 sets of color data (C, M, Y, K),which will possibly be inputted to the color correction process of S100,are prepared, wherein C=0, 31, 63, 95, 127, 159, 191, 223, and 255, M=0,31, 63, 95, 127, 159, 191, 223, and 255, Y=0, 31, 63, 95, 127, 159, 191,223, and 255, and K=0, 31, 63, 95, 127, 159, 191, 223, and 255. Each setof color data (C, M, Y, K) is outputted, without being subjected to anycorrection or conversion process, to a standard printer to produce 6,561color patches. The color patches are measured by a colorimeter to obtainthe L*a*b color values (L, a, b) of the color patches. Interpolationcalculation is performed on the measured L*a*b* color values and theoriginal color values (C, M, Y, K) to determine a relationship between aplurality of color values (C, M, Y, K), which are to be inputted to thecolor-correction process of S100, and a plurality of Lab color values(L, a, b). It is noted that the relationship between color data (C, M,Y, K) and the L*a*b color values (L, a, b) can be determined also basedon a (CMYK-Lab) look up table that is supplied from Pantone Corporationor SWOP (Standard Wet Offset Printing). As a result, the relationshipamong color data (C, M, Y, K), to be inputted to the process of S100,L*a*b* color data (L, a, b), and color-corrected color data (C′, M′, Y′,K′), to be outputted from the process of S100, is obtained. Therefore, adirect relationship between color data (C, M, Y, K) and color-correctedcolor data (C′, M′, Y′, K′) is obtained. Thus, the color correctiontable T1 is obtained.

It is noted that the color correction table T1 may be produced in amanner described in U.S. Pat. No. 4,500,919.

Because the tables T1, T2 (T2 c, T2 m, T2 y, and T2 k), T3 (T3 cl, T3cn, T3 ml, and T3 nm), and T4 (T4 cl, T4 cn, T4 ml, and T4 nm) areprepared as described above, the image conversion process of FIG. 5 isperformed using those tables in a manner described below.

In S100, input color data (Ci, Mi, Yi, Ki), prepared in an imagepreparation application or the like, is color-corrected intocolor-corrected color data (Ci′, Mi′, Yi′, Ki′) using the colorcorrection table T1. More specifically, if input color data (Ci, Mi, Yi,Ki) matches with some set of color data (C, M, Y, K) in the colorcorrection table T1, the input color data (Ci, Mi, Yi, Ki) is directlycolor-corrected into a set of color-corrected color data (Ci′, Mi′, Yi′,Ki′) that is stored in the color correction table T1 in correspondencewith the matching color data (C, M, Y, K). On the other hand, if theinput color data (Ci, Mi, Yi, Ki) matches with no color data (C, M, Y,K) in the color correction table T1, then a set of approximatecolor-corrected data (Ci′, Mi′, Yi′, Ki′) is calculated by interpolatingseveral sets of color-corrected data (C′, M′, Y′, K′), which are storedin the table T1 for several sets of color data (C, M, Y, K) thatsurround the subject set of input color data (Ci, Mi, Yi, Ki). Thus,each set of input color data (Ci, Mi, Yi, Ki) is color-corrected intocolor-corrected color data (Ci′, Mi′, Yi′, Ki′) so as to be suitablyreproduced by a combination of four colors of cyan, magenta, yellow, andblack.

Then, in S200, using the tone correction tables T2 c, T2 m, T2 y, and T2k, values of color data (Ci′, Mi′, Yi′, Ki′), which has already beensubjected to the color correction processes of S100, are subjected totone correction. During the tone correction process for cyan component,the value Ci′ of the color-corrected input color data (Ci′, Mi′, Yi′,Ki′) is used to refer to the horizontal axis in the tone-correctiontable T2 c (FIG. 7) for cyan color. Then, with respect to thecolor-corrected data Ci′ (horizontal axis), the value of tone-correctedcolor data Ci″ (right-hand vertical axis) on the tone-correction curveis obtained. Thus, a color-and-tone-corrected color data Ci″ is obtainedfor the color-corrected color data Ci′. The same operation is performedfor other remaining values Mi′, Yi′, and Ki′ by using thetone-correction tables T2 m, T2 y, and T2 k (FIG. 7) for magenta,yellow, and black colors. As a result, one set ofcolor-and-tone-corrected color data (Ci″, Mi″, Yi″, Ki″) is producedbased on each set of color-corrected color data (Ci′, Mi′, Yi′, Ki′).

Then, in S300, using the conversion tables T3 cl and T3 cn for cyancolor, the value Ci″ is converted into values Cl and Cn. Similarly,using the conversion tables T3 ml and T3 nm for magenta color, the valueMi″ is converted into values Ml and Mn. More specifically, during theconversion process for cyan, the value Ci″ is used to refer to thehorizontal axis of FIG. 8, which is represented by the conversion tablesT3 cl and T3 cn (FIGS. 9(a) and 9(b)). Then, with respect to the valueof the color-and-tone-corrected data Ci″ (horizontal axis), a value Clof light ink color data (vertical axis) is obtained on the light inkconversion line (broken line) and a value Cn of normal ink color data(vertical axis) is obtained on the normal ink conversion line (solidline). Thus, light ink color data Cl and normal ink color data Cn areobtained. In other words, the color-and-tone-corrected color data Ci″ isconverted into ink data (Cl, Cn). The same operation as described aboveis performed for magenta color component by using the conversion tablesT3 nm and T3 ml. Thus, light cyan ink data Cl, normal cyan ink data Cn,light magenta ink data Ml, and normal magenta ink data Mn are produced.

Then, in S400, using the tone correction table T4 cl for light cyan ink,the light cyan ink value Cl is tone-corrected into a tone-correctedlight cyan ink value Cl′. Similarly, using the tone correction table T4cn for normal cyan ink, the normal cyan ink value Cn is tone-correctedinto a tone-corrected normal cyan ink value Cn′. Using the tonecorrection table T4 ml for light magenta ink, the light magenta inkvalue Ml is tone-corrected into a tone-corrected light magenta ink valueMl′. Similarly, using the tone correction table T4 nm for normal magentaink, the normal magenta ink value Mn is tone-corrected into atone-corrected normal magenta ink value Mn′. More specifically, duringthe tone correction process for light cyan ink, the value Cl is used torefer to the horizontal axis in the tone-correction table T4 cl (FIG.10) for light cyan ink. Then, with respect to the value Cl (horizontalaxis), the value of tone-corrected ink data Cl′ (right-hand verticalaxis) on the tone-correction curve is obtained. Thus, tone-corrected inkdata Cl′ is obtained for the ink data Cl. The same operation isperformed for other remaining values Cn, Ml, and Mn by using thetone-correction tables T4 cn, T4 ml, and T4 nm (FIG. 10) for normalcyan, light magenta, and normal magenta inks.

The thus produced tone-corrected ink data Cl′, Cn′, Ml′, and Mn′ areoutputted together with the color data Yi″ and Ki″ for yellow and blackcomponents. Thus, a set of data (Cl′, Cn′, Ml′, Mn′, Yi″, Ki″) isobtained based on each set of original input color data (Ci, Mi, Yi,Ki).

Then, in S500, the thus obtained data set (Cl′, Cn′, Ml′, Mn′, Yi″,Ki″), which has been subjected to the several correction and conversionprocesses as described above, is subjected to a binarization processesin the well known manner such as those described in the U.S. Pat. No.5,045,952. Then, a resultant binary signal (Cl_(o), Cn_(o), Ml_(o)Mn_(o), Y_(o), K_(o)) is outputted to the color printer 2. The printunit 21 is controlled in S600 to print a color image on the imagerecording medium based on the binary signal (Cl_(o), Cn_(o), Ml_(o),Mn_(o), Y_(o), K_(o)).

It is noted that data of the color-correction table T1 and theconversion tables T3 cl, T3 cn, T3 ml, and T3 nm is stored in the harddisk 14 as unchangeable, fixed data. However, data of thetone-correction tables T2 c, T2 m, T2 y, and T2 k (upstream profile U)and the tone-correction tables T4 cl, T4 cn, T4 ml, and T4 nm(downstream profile D) can be changed or updated according to changes inthe printer characteristics. That is, data of the tone-correction tablesT2 c, T2 m, T2 y, and T2 k and the tone-correction tables T4 cl, T4 cn,T4 ml, and T4 nm can be changed when the characteristics of the printer2 changes by passage of time. Data of the tone-correction tables T2 c,T2 m, T2 y, and T2 k and the tone-correction tables T4 cl, T4 cn, T4 ml,and T4 nm can be changed also when the model of the printer 2 ischanged, the type of image recording medium used in the printer 2 ischanged, the type of ink used is changed, the resolution set in theprinter 2 is changed, or the printing speed set in the printer 2 ischanged.

When the user desires to update data of the tone-correction tables T2 c,T2 m, T2 y, and T2 k and data of the tone-correction tables T4 cl, T4cn, T4 ml, and T4 nm, the user instructs the profile preparation system100 to start executing the profile preparation process of FIG. 3 toupdate data of the tone-correction tables T2 c, T2 m, T2 y, and T2 k asdata of the upstream profile U and to update data of the tone-correctiontables T4 cl, T4 cn, T4 ml, and T4 nm as data of the downstream profileD.

During the downstream profile production process of S2-S4 (FIG. 3), dataof the tone-correction tables T4 cl, T4 cn, T4 ml, and T4 nm is preparedas a downstream profile D in the same manner as for when thetone-correction tables T4 cl, T4 cn, T4 ml, and T4 nm are initiallyproduced.

More specifically, in order to prepare the tone correction table T4 cl,in S2, nine sets of light cyan ink data Cl of 0, 31, 63, 95, 127, 159,191, 223, and 255 are prepared. By subjecting the nine sets of ink dataCl to no tone-correction process, nine sets of ink data Cl′ having thetone values 0, 31, 63, 95, 127, 159, 191, 223, and 255 are obtained. Thenine sets of ink data Cl′ are binarized in the same manner as in theprocess of S500, and supplied to the printer 2. As a result, nine colorpatches are produced as shown in FIG. 2(b).

Next, in S3, the output density level of each color patch is measuredusing the calorimeter 5. Then, in S4, a measurement curve is prepared,based on the measurement results, as indicated by aone-dot-and-one-chain line in FIG. 10. Then, as indicated by a brokenline in the same figure, a tone-correction curve is calculated, and isset as a tone-correction table T4 cl.

It is noted that the tone correction tables T4 cn, T4 ml, and T4 nm areprepared for normal cyan ink, light magenta ink, and normal magenta inkin the same manner as described above for light cyan ink.

During the downstream profile examination process of S6-S8, the table T4cl is examined in a manner described below.

First, in S6, nine sets of light cyan ink data Cl of 0, 31, 63, 95, 127,159, 191, 223, and 255 are prepared, and are tone-corrected intotone-corrected ink data Cl′ by using the table T4 cl which has just beenprepared in S4. Then, each set of tone-corrected ink data Cl′ isbinarized into binarized data Clo, and is supplied to the printer 2. Asa result, the print unit 21 is controlled to print nine single-inkpatches as shown in FIG. 2(b) using light cyan ink.

Then, in S7, the nine single-ink patches are measured by the colorimeter5, and examination is performed in S8 whether the density of the colorpatches increases in the monotone nondecreasing manner in accordancewith the increase in the value of the original ink data Cl.

More specifically, the CPU 11 judges in S8 whether or not thetone-correction table T4 cl is suitable by confirming whether themeasured density levels of all the nine color patches increase from oneto the next color patch in the expected monotone nondecreasing manner.In other words, the CPU 11 judges whether or not the measured densitylevel of each color patch is higher than or equal to its preceding colorpatch.

It is now assumed that the density level of each color patch has a valueD(i) (where i is the order of the subject color patch, 0≦i≦8). The CPU11 judges in S8 whether or not the value D(i) of each color patch (i:0≦i≦8) is smaller than or equal to the value D(i+1) of the next colorpatch (i+1). In other words, the CPU 11 judges whether the followinginequality (1) is satisfied:D(i)≦D(i+1)  (1)

-   -   wherein 0≦i≦8.

The CPU 11 determines that the table T4 cl is unsuitable when at leastone of the nine color patches (i) does not satisfy the inequality (1).The CPU 11 determines that the table T4 cl is suitable when all the ninecolor patches satisfy the inequality (1).

Alternatively, the CPU 11 may judge in S8 whether the measured densitylevel of each color patch is within the desirable range predeterminedfor the subject color patch. The CPU 11 determines that the table T4 clis suitable when the measured density level D(i) of each color patch (i)is within its desirable range. The CPU 11 determines that the table T4cl is unsuitable when the measured density level D(i) of at least onecolor patch (i) is out of its desirable range.

The tables T4 cn, T4 ml, and T4 nm are examined in the same manner asdescribed above for table T4 cl.

It is noted that in S8, the CPU 11 further judges whether or not all ofthe four tables T4 cl, T4 cn, T4 ml, and T4 nm are suitable. The CPUdetermines that the downstream profile D is suitable only when all ofthe four tables T4 cl, T4 cn, T4 ml, and T4 nm are suitable. The CPU 11determines that the downstream profile D is unsuitable when at least oneof the four tables T4 cl, T4 cn, T4 ml, and T4 nm is unsuitable.

During the upstream profile production process of S9, data of thetone-correction tables T2 c, T2 m, T2 y, and T2 k is prepared as anupstream profile U in the same manner as when the tone-correction tablesT2 c, T2 m, T2 y, and T2 k are initially produced.

More specifically, in order to prepare the table T2 c, in S9, nine setsof color data C′ of 0, 31, 63, 95, 127, 159, 191, 223, and 255 areprepared. By subjecting the nine sets of color data C′ to notone-correction process, nine sets of color data C″ having the values 0,31, 63, 95, 127, 159, 191, 223, and 255 are obtained. Then, the ninesets of color data C″ are converted into nine sets of ink data (Cn, Cl)by using the conversion tables T3 cn and T3 cl, which are stored in thehard disk 14. Then, the nine sets of ink data (Cn, Cl) aretone-corrected into nine sets of tone-corrected ink data (Cn′, Cl′) byusing the tone-correction tables T4 cn and T4 cl, which have just beenprepared in S4. Then, the nine sets of ink data (Cn′, Cl′) are binarizedin the same manner as in the process of S500, and supplied to theprinter 2. As a result, nine color patches are produced as shown in FIG.2(b). Then, the output density level of each color patch is measuredusing the colorimeter 5. Based on the measurement results of the ninecolor patches, a measurement curve is prepared, as indicated by aone-dot-and-one-chain line in FIG. 7. Then, a tone-correction curve iscalculated as indicated by a broken line in the same figure, and set asa tone-correction table T2 c.

The tone-correction table T2 m is prepared in the same manner asdescribed for cyan color.

In order to prepare the tone correction table T2 y for yellow color, inS9, nine sets of yellow color data Y′ of 0, 31, 63, 95, 127, 159, 191,223, and 255 are prepared, binarized in the same manner as in theprocess of S500, and are supplied to the printer 2. As a result, ninecolor patches are produced by yellow ink as shown in FIG. 2(b).Densities of the nine color patches are measured by the calorimeter 5.Based on the measured results, a measurement curve(one-dot-and-one-chain line) of FIG. 7 is obtained. Then, atone-correction curve (broken line) is determined and set as atone-correction table T2 y.

It is noted that the tone correction table T2 k is prepared for blackcolor in the same manner as described above for yellow color.

During the upstream profile examination process of S11-S13, the table T2c is examined in a manner described below. It is noted that the table T2m is examined in the same manner as described below for table T2 c.

First, in S11, nine sets of color data C′ of 0, 31, 63, 95, 127, 159,191, 223, and 255 are prepared, and tone-corrected into tone-correctedcolor data C″ by using the table T2 c which has just been prepared inS9. Then, the thus obtained nine sets of tone-corrected color data C″are converted into nine sets of ink data (Cl, Cn) by using the tables T3cn and T3 cl which are stored in the hard disk 14. The thus obtainednine sets of ink data (Cl, Cn) are then tone-corrected into (Cl′, Cn′)by using the tables T4 cl and T4 cn which have just been prepared in S4.Then, the nine sets of tone-corrected ink data (Cl′, Cn′) are binarizedinto binarized data (Clo, Cno), and are supplied to the printer 2. As aresult, nine color patches are printed on a recording medium as shown inFIG. 2(b) by using light cyan ink and normal cyan ink.

Then, in S12, the output density level of each color patch is measuredusing the calorimeter 5. Examination is performed in S13 whether thedensity of the color patch properly increases in the monotonenondecreasing manner in accordance with the increase in the value of theoriginal color data C′. The examination is performed in S13 in the samemanner as in S8. That is, the CPU 11 determines that at least one of thetables T2 c, T4 cl, and T4 cn is unsuitable when at least one of thenine color patches (i) does not satisfy the inequality (1). The CPU 11determines that all of the tables T2 c, T4 cl, and T4 cn are suitablewhen all the nine color patches satisfy the inequality (1).Alternatively, the CPU 11 may determine in S13 that all of the tables T2c, T4 cl, and T4 cn are suitable when the measured density level D(i) ofeach color patch (i) is within its desirable range. The CPU 11determines that at least one of the tables T2 c, T4 cl, and T4 cn isunsuitable when the measured density level D(i) of at least one colorpatch (i) is out of its desirable range.

During the upstream profile examination process of S11-S13, the table T2y is examined in a manner described below. It is noted that the table T2k is examined in the same manner as described below for table T2 y.

First, in S11, nine sets of color data Y′ of 0, 31, 63, 95, 127, 159,191, 223, and 255 is tone-corrected into tone-corrected color data Y″ byusing the table T2 y which has just been prepared in S9. Then, nine setsof tone-corrected color data Y″ are binarized into binarized data Yo andsupplied to the printer 2. As a result, the print unit 21 is controlledto print nine color patches using yellow ink.

The nine single-color patches are then measured in S12 by thecalorimeter 5, and examination is performed in S13 whether the densityof the color patch properly increases in the monotone nondecreasingmanner in accordance with the increase in the value of the originalcolor data Y′. The examination is performed in the same manner as in S8.That is, the CPU 11 determines that the table T2 y is unsuitable when atleast one of the nine color patches (i) does not satisfy the inequality(1). The CPU 11 determines that the table T2 y is suitable when all thenine color patches satisfy the inequality (1). Alternatively, the CPU 11may determine that the table T2 y is suitable when the measured densitylevel D(i) of each color patch (i) is within its desirable range. TheCPU 11 determines that the table T2 y is unsuitable when the measureddensity level D(i) of at least one color patch (i) is out of itsdesirable range.

It is noted that in S13, the CPU further determines whether or not allof the tables T2 c, T4 cl, and T4 cn, T4 m, T4 ml, and T4 nm, T2 y, andT2 k are suitable. The CPU determines that both of the upstream profileU and the downstream profile D are suitable only when all of the eighttables T2 c, T4 cl, and T4 cn, T4 m, T4 ml, and T4 nm, T2 y, and T2 kare suitable. The CPU determines that one or both of the upstreamprofile U and the downstream profile D is unsuitable when at least oneof the tables T2 c, T4 cl, and T4 cn, T4 m, T4 ml, and T4 nm, T2 y, andT2 k is unsuitable.

It is noted that in the above description, during the downstream profileexamination processes of S6-S8, color patches are produced in S6 bypreparing nine light cyan values Cl of 0-255. The results measured in S7for the light cyan ink can therefore be used to prepare the measurementcurve for cyan (one-dot-and-one-chain line in FIG. 7) in the range lowerthan the reference value C′ of 127. This is because the measurementcurve in that range is produced only by light cyan ink. Accordingly, thetone correction curve or upstream profile T2 c (broken line in FIG. 7)for cyan in the range lower than the reference tone can be preparedbased on the measurement results taken in S7. Similarly, the resultsmeasured in S7 for light magenta ink can also be used to prepare themeasurement curve for magenta in the range lower than the referencevalue M′ of 127. Accordingly, the tone correction curve T2 m (upstreamprofile) for magenta in the range lower than the reference tone can beprepared based on the measurement results taken in S7.

In the above-described example, during the upstream profile preparationprocess of S9, color patches are printed and measured. Then, based onthe measured results, the tables T2 c, T2 m, T2 y, and T2 k (upstreamprofile) is prepared. However, if the results measured in S7 during thedownstream profile examination procedure can be directly used forpreparing the tables T2 c, T2 m, T2 y, and T2 k (upstream profile), itis unnecessary to perform the color patch printing process or the colorpatch measuring process during the process of S9.

While the invention has been described in detail with reference to thespecific embodiment thereof, it would be apparent to those skilled inthe art that various changes and modifications may be made thereinwithout departing from the spirit of the invention, the scope of whichis defined by the attached claims.

For example, the embodiment described above is applied to a profilepreparation process for preparing the tone correction upstream profileand the tone correction downstream profile. However, the presentinvention could be applied to any process for preparing a variety ofinterrelated profiles, of upstream and downstream profiles.

Also, the present invention is not limited to a process for preparingtwo types of profiles, but could also be applied to a process forpreparing three or more profiles.

The embodiment describes measuring density level of the color patches tomeasure color of the color patches for preparing profiles. However, itis possible to measure other values defined according to L*a*b* orL*u*v* calorimetric systems, defined by the CIE (CommissionInternationale de l'Eclairage), and the like.

The embodiment describes judging whether profile preparation is to beterminated, directly after preparing the downstream profile and directlyafter preparing the upstream profile. However, this judgment aboutprofile preparation termination could be made at any timing, asnecessity dictates.

Also, in the embodiment, the program always returns to the processes forpreparing the downstream profile, whenever it is judged that thedownstream profile is improperly prepared. However, the system can bedesigned to first notify the user that the downstream profile has beenimproperly prepared, and then enable the user to select whether tocontinue profile preparation processes. Similarly, the program alwaysreturns to the processes for preparing the downstream profile, wheneverit is judged that the upstream and/or downstream profile is improperlyprepared. However, the system can be designed to first notify the userthat at least one profile has been improperly prepared, and then enablethe user to select whether to continue profile preparation processes.

More specifically, a step of S20 may be added between the processes ofS14 and S15 as shown in FIG. 4. In this case, in S14, the CRT display 16is first controlled to display that the presently-prepared profile(s)has been improperly prepared. Then, in S20, the CRT display 16 isfurther controlled to display a message asking the user whether he/shedesires to continue the profile preparation processes. Upon viewing themessage, the user inputs, via the input unit 18, his/her confirmationwhether he/she desires to continue the present profile preparationprocesses. When the user confirms his/her desire to continue the presentprocesses (yes in S20), the program proceeds via the process of S15 toreturn to S2. On the other hand, when the user confirms his/her desirenot to continue the present processes (no in S20), the program proceedsto the process of S16, and the process is ended.

1. A method for updating profiles, comprising: storing a plurality ofsuccessive profiles for an image recording device, the profiles beingsuccessively used to process image data that is used for recordingimages on a recording medium by the image recording device; and changingat least two of the successive profiles when characteristics of theimage recording device change.
 2. A method as claimed in claim 1,wherein the at least two of the successive profiles are changed when thecharacteristics of the image recording device change over passage oftime.
 3. A method as claimed in claim 1, wherein the at least two of thesuccessive profiles are changed when a model of the image recordingdevice is changed.
 4. A method as claimed in claim 1, wherein the atleast two of the successive profiles are changed when a type of theimage recording medium used is changed.
 5. A method as claimed in claim1, wherein the at least two of the successive profiles are changed whena type of ink used in the image recording device is changed.
 6. A methodas claimed in claim 1, wherein the at least two of the successiveprofiles are changed when a setting of a resolution in the imagerecording device is changed.
 7. A method as claimed in claim 1, whereinthe at least two of the successive profiles are changed when a settingof a printing speed in the image recording device is changed.
 8. Amethod as claimed in claim 1, wherein the plurality of successiveprofiles include at least an upstream profile and a downstream profile,the upstream profile being used for performing a prior process on theimage data and the downstream profile being used for performing asubsequent process on the image data already processed by the priorprocess, the upstream profile and the downstream profile being changedwhen the characteristics of the image recording device change.
 9. Amethod as claimed in claim 1, wherein the changing step includes:preparing a new downstream profile; preparing a new upstream profileusing the prepared new downstream profile; and writing the newdownstream profile and the new upstream profile over the already-storeddownstream and upstream profiles.
 10. A method as claimed in claim 9,wherein the changing step further includes judging, after the newdownstream profile preparation process and before the new upstreamprofile preparation process, whether the new downstream profile has beenproperly prepared by processing image data using the prepared newdownstream profile, by controlling the image recording device to recordthe processed image data on a recording medium, by examining a recordedresult, and by judging whether or not the new downstream profile hasbeen properly prepared based on the examined result, and when it isjudged that the new downstream profile has been improperly prepared,preventing the new upstream profile preparation process from beingperformed based on the improperly-prepared new downstream profile.
 11. Amethod as claimed in claim 10, wherein the prevention process includesthe step of terminating preparation of the new upstream and downstreamprofiles.
 12. A method as claimed in claim 10, wherein the judgmentprocess restarts the new downstream profile preparation process when itis judged that the new downstream profile has been improperly prepared.13. A method as claimed in claim 10, wherein the changing step furtherincludes: setting the already-stored downstream profile and the upstreamprofile as an initial downstream profile and an initial upstreamprofile, respectively; and judging, after the new upstream profilepreparation process, whether the prepared new upstream profile and thenew downstream profile have been properly prepared by processing imagedata using the prepared new upstream profile in a prior process, byfurther processing the processed image data using the prepared newdownstream profile in a subsequent process, by controlling the imagerecording device to record on a recording medium the image dataprocessed using both of the new upstream profile and the new downstreamprofile, by examining a recorded result, and by judging whether the newupstream profile and the new downstream profile have been properlyprepared based on the examined result, and when it is judged that atleast one of the new upstream profile and the new downstream profile hasbeen improperly prepared, restoring the new downstream and upstreamprofiles to the initial downstream and upstream profiles.
 14. A methodas claimed in claim 13, wherein the changing step further includes,after the restoring process, a step of terminating preparation of thenew upstream profile and the new downstream profile.
 15. A method asclaimed in claim 13, wherein the changing step further includes, afterthe restoring process, a step of restarting the new downstream profilepreparation process.
 16. A device for updating profiles, comprising: amemory that stores a plurality of successive profiles for an imagerecording device, the profiles being successively used to process imagedata that is used for recording images on a recording medium by theimage recording device; and a changing unit that changes at least two ofthe successive profiles when characteristics of the image recordingdevice change.
 17. A device as claimed in claim 16, wherein the changingunit changes the at least two of the successive profiles when thecharacteristics of the image recording device change over passage oftime.
 18. A device as claimed in claim 16, wherein the changing unitchanges the at least two of the successive profiles when a model of theimage recording device is changed.
 19. A device as claimed in claim 16,wherein the changing unit changes the at least two of the successiveprofiles when a type of the image recording medium used is changed. 20.A device as claimed in claim 16, wherein the changing unit changes theat least two of the successive profiles when a type of ink used in theimage recording device is changed.
 21. A device as claimed in claim 16,wherein the changing unit changes the at least two of the successiveprofiles when a setting of a resolution in the image recording device ischanged.
 22. A device as claimed in claim 16, wherein the changing unitchanges the at least two of the successive profiles when a setting of aprinting speed in the image recording device is changed.
 23. A device asclaimed in claim 16, wherein the plurality of successive profilesinclude at least an upstream profile and a downstream profile, theupstream profile being used for performing a prior process on the imagedata and the downstream profile being used for performing a subsequentprocess on the image data already processed by the prior process, thechanging unit changing the upstream profile and the downstream profilewhen the characteristics of the image recording device change.
 24. Adevice as claimed in claim 23, wherein the changing unit includes: adownstream profile preparing unit preparing a new downstream profile; anupstream profile preparing unit preparing a new upstream profile usingthe prepared new downstream profile; and a writing unit writing the newdownstream profile and the new upstream profile in the memory over thealready-stored downstream and upstream profiles.
 25. A device as claimedin claim 24, wherein the changing unit further includes a judging unitjudging, after the new downstream profile preparation process and beforethe new upstream profile preparation process, whether the new downstreamprofile has been properly prepared by processing image data using theprepared new downstream profile, by controlling the image recordingdevice to record the processed image data on a recording medium, byexamining a recorded result, and by judging whether the new downstreamprofile has been properly prepared based on the examined result, andwhen it is judged that the new downstream profile has been improperlyprepared, preventing the upstream profile preparation unit fromperforming the preparation based on the improperly-prepared newdownstream profile.
 26. A device as claimed in claim 25, wherein thejudging unit controls the upstream and downstream profile preparingunits to terminate preparation of the new upstream profile and the newdownstream profile, thereby preventing the upstream profile preparationunit from performing the preparation based on the improperly-preparednew downstream profile.
 27. A device as claimed in claim 25, wherein thejudging unit controls the downstream profile preparing unit to restartthe new downstream profile preparation process when it is judged thatthe new downstream profile has been improperly prepared.
 28. A device asclaimed in claim 25, wherein the changing unit further includes asetting unit setting the presently-existing downstream profile and thepresently-existing upstream profile as an initial downstream profile andan initial upstream profile, respectively; and wherein the judging unitjudges, after the upstream profile preparation process, whether theprepared new upstream profile and the new downstream profile have beenproperly prepared by processing image data using the prepared newupstream profile in a prior process, by further processing the processedimage data using the prepared new downstream profile in a subsequentprocess, by controlling the image recording device to record on arecording medium the image data processed using both of the new upstreamprofile and the new downstream profile, by examining a recorded result,and by judging whether or not the new upstream profile and the newdownstream profile have been properly prepared based on the examinedresult, and when it is judged that at least one of the new upstreamprofile and the new downstream profile has been improperly prepared,restores the new downstream and upstream profiles to the initialdownstream and upstream profiles.
 29. A device as claimed in claim 28,wherein the judging unit controls, after the restoring process, theupstream and downstream profile preparing unit to terminate thepreparation of the new upstream profile and the new downstream profile.30. A device as claimed in claim 28, wherein the judging unit controls,after the restoring process, the downstream profile preparing unit torestart the downstream profile preparation process.
 31. A method forupdating profiles, comprising: storing a plurality of successiveprofiles for an image recording device, the profiles being successivelyused to process image data that is used for recording images on arecording medium by the image recording device; and changing at leasttwo of the successive profiles upon receipt of a user's instruction. 32.A method as claimed in claim 31, wherein the plurality of successiveprofiles include at least an upstream profile and a downstream profile,the upstream profile being used for performing a prior process on theimage data and the downstream profile being used for performing asubsequent process on the image data already processed by the priorprocess, wherein the changing step includes: preparing a new downstreamprofile; preparing a new upstream profile using the prepared newdownstream profile; and writing the new downstream profile and the newupstream profile over the already-stored downstream and upstreamprofiles.
 33. A method as claimed in claim 32, wherein the changing stepfurther includes judging, after the new downstream profile preparationprocess and before the new upstream profile preparation process, whetherthe new downstream profile has been properly prepared by processingimage data using the prepared new downstream profile, by controlling theimage recording device to record the processed image data on a recordingmedium, by examining a recorded result, and by judging whether or notthe new downstream profile has been properly prepared based on theexamined result, and when it is judged that the new downstream profilehas been improperly prepared, preventing the new upstream profilepreparation process from being performed based on theimproperly-prepared new downstream profile.
 34. A method as claimed inclaim 33, wherein the prevention process includes the step ofterminating preparation of the new upstream and downstream profiles. 35.A method as claimed in claim 33, wherein the judgment process restartsthe new downstream profile preparation process when it is judged thatthe new downstream profile has been improperly prepared.
 36. A method asclaimed in claim 33, wherein the changing step further includes: settingthe already-stored downstream profile and the upstream profile as aninitial downstream profile and an initial upstream profile; and judging,after the new upstream profile preparation process, whether the preparednew upstream profile and the new downstream profile have been properlyprepared by processing image data using the prepared new upstreamprofile in a prior process, by further processing the processed imagedata using the prepared new downstream profile in a subsequent process,by controlling the image recording device to record on a recordingmedium the image data processed using both of the new upstream profileand the new downstream profile, by examining a recorded result, and byjudging whether the new upstream profile and the new downstream profilehave been properly prepared based on the examined result, and when it isjudged that at least one of the new upstream profile and the newdownstream profile has been improperly prepared, restoring the newdownstream and upstream profiles to the initial downstream and upstreamprofiles.
 37. A method as claimed in claim 36, wherein the changing stepfurther includes, after the restoring process, the step of terminatingpreparation of the new upstream profile and the new downstream profile.38. A method as claimed in claim 36, wherein the changing step furtherincludes, after the restoring process, the step of restarting the newdownstream profile preparation process.
 39. A device for updatingprofiles, comprising: a memory that stores a plurality of successiveprofiles for an image recording device, the profiles being successivelyused to process image data that is used for recording images on arecording medium by the image recording device; and a changing unit thatchanges at least two of the successive profiles upon receipt of a user'sinstruction.
 40. A device as claimed in claim 39, wherein the pluralityof successive profiles include at least an upstream profile and adownstream profile, the upstream profile being used for performing aprior process on the image data and the downstream profile being usedfor performing a subsequent process on the image data already processedby the prior process, and wherein the changing unit includes: adownstream profile preparing unit preparing a new downstream profile; anupstream profile preparing unit preparing a new upstream profile usingthe prepared new downstream profile; and a writing unit writing the newdownstream profile and the new upstream profile in the memory over thealready-stored downstream and upstream profiles.
 41. A device as claimedin claim 40, wherein the changing unit further includes a judging unitjudging, after the new downstream profile preparation process and beforethe new upstream profile preparation process, whether the new downstreamprofile has been properly prepared by processing image data using theprepared new downstream profile, by controlling the image recordingdevice to record the processed image data on a recording medium, byexamining a recorded result, and by judging whether the new downstreamprofile has been properly prepared based on the examined result, andwhen it is judged that the new downstream profile has been improperlyprepared, preventing the upstream profile preparation unit fromperforming the preparation based on the improperly-prepared newdownstream profile.
 42. A device as claimed in claim 41, wherein thejudging unit controls the upstream and downstream profile preparingunits to terminate preparation of the new upstream profile and the newdownstream profile, thereby preventing the upstream profile preparationunit from performing the preparation based on the improperly-preparednew downstream profile.
 43. A device as claimed in claim 41, wherein thejudging unit controls the downstream profile preparing unit to restartthe new downstream profile preparation process when it is judged thatthe new downstream profile has been improperly prepared.
 44. A device asclaimed in claim 41, wherein the changing unit further includes aupstream profile as an initial downstream profile and an initialupstream profile; and wherein the judging unit judges, after theupstream profile preparation process, whether the prepared new upstreamprofile and the new downstream profile have been properly prepared byprocessing image data using the prepared new upstream profile in a priorprocess, by further processing the processed image data using theprepared new downstream profile in a subsequent process, by controllingthe image recording device to record on a recording medium the imagedata processed using both of the new upstream profile and the newdownstream profile, by examining a recorded result, and by judgingWhether or not the new upstream profile and the new downstream profilehave been properly prepared based on the examined result, and when it isjudged that at least one of the new upstream profile and the newdownstream profile has been improperly prepared, restores the newdownstream and upstream profiles to the initial downstream and upstreamprofiles.
 45. A device as claimed in claim 44, wherein the judging unitcontrols, after the restoring process, the upstream and downstreamprofile preparing unit to terminate the preparation of the new upstreamprofile and the new downstream profile.
 46. A device as claimed in claim44, wherein the judging unit controls, after the restoring process, thedownstream profile preparing unit to restart the downstream profilepreparation process.
 47. A method for updating profiles, comprising:storing a plurality of successive profiles for an image recordingdevice, the profiles being successively used to process image data thatis used for recording images on a recording medium by the imagerecording device; inputting an instruction when characteristics of theimage recording device change; and starting to change at least two ofthe successive profiles in response to the input of the instruction. 48.A method as claimed in claim 47, wherein the plurality of successiveprofiles include at least an upstream profile and a downstream profile,the upstream profile being used for performing a prior process on theimage data and the downstream profile being used for performing asubsequent process on the image data already processed by the priorprocess, wherein the changing step includes: preparing a new downstreamprofile; preparing a new upstream profile using the prepared newdownstream profile; and writing the new downstream profile and the newupstream profile over the already-stored downstream and upstreamprofiles.
 49. A device for updating profiles, comprising: a memory thatstores a plurality of successive profiles for an image recording device,the profiles being successively used to process image data that is usedfor recording images on a recording medium by the image recordingdevice; an instruction input unit that receives a user's instructionwhen characteristics of the image recording device change; and achanging unit that changes at least two of the successive profiles uponreceipt of a user's instruction.
 50. A device as claimed in claim 49,wherein the plurality of successive profiles include at least anupstream profile and a downstream profile, the upstream profile beingused for performing a prior process on the image data and the downstreamprofile being used for performing a subsequent process on the image dataalready processed by the prior process, and wherein the changing unitincludes; a downstream profile preparing unit preparing a new downstreamprofile; an upstream profile preparing unit preparing a new upstreamprofile using the prepared new downstream profile; and a writing unitwriting the new downstream profile and the new upstream profile in thememory over the already-stored downstream and upstream profiles.